What causes fault code CONV-004 (Conveyor Photoeye Blocked)?

Product jammed at sensor location — physical obstruction. Photoeye lens dirty — dust, grease, or moisture. Photoeye misaligned — emitter and receiver not pointing at each other. Sensor cable damaged or disconnected. Retro-reflector missing, fallen off, or dirty (retro-reflective type). Sensor sensitivity set too high — picking up background objects

How do I fix fault code CONV-004?

Clear any product jam at the sensor location. Clean sensor lens with soft cloth — both emitter and receiver if through-beam. Realign sensor — use alignment indicator LED on sensor body. Check wiring connections at sensor and PLC input module. Clean or replace retro-reflector (if retro-reflective type). Adjust sensitivity trim pot — start low and increase until reliable. Replace sensor if LED indicators show fault after cleaning and realignment

Conveyor Photoeye Blocked

CONV-004

Photoeye sensor continuously in blocked state. Product may be stuck, sensor may be misaligned, or wiring fault.

low conveyor packaging

conveyor photoeye sensor jam alignment

Probable Causes (ranked)

Product jammed at sensor location — physical obstruction
Photoeye lens dirty — dust, grease, or moisture
Photoeye misaligned — emitter and receiver not pointing at each other
Sensor cable damaged or disconnected
Retro-reflector missing, fallen off, or dirty (retro-reflective type)
Sensor sensitivity set too high — picking up background objects

Fix Steps

1 Clear any product jam at the sensor location
2 Clean sensor lens with soft cloth — both emitter and receiver if through-beam
3 Realign sensor — use alignment indicator LED on sensor body
4 Check wiring connections at sensor and PLC input module
5 Clean or replace retro-reflector (if retro-reflective type)
6 Adjust sensitivity trim pot — start low and increase until reliable
7 Replace sensor if LED indicators show fault after cleaning and realignment

Field Trick

Cover the emitter with your hand. If the PLC input doesn't change, the problem is wiring/PLC, not the photoeye. If it does change, realign or clean.

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